View Full Version : V1-P Additional info.


Michael Phillips
December 28th, 2006, 03:32 PM
I have some additional information that may make the issue of viewing 25P footage a little clearer.

1. The raw footage (new section of a brick house) from the camera whether directly viewed via HDMI on a Panasonic HD plasma TV or captured and viewed on a computer monitor shows clearly the crawling edges.The same clip shot in 50i mode shows no such abberation.

2. I put the clip into Vegas and viewed before I did anything to it. All the brick joins crawled but the preview in Vegas at Preview resolution is not good but did emphasize what was happening. Made some cuts and rendered to HDV PAL Mpeg Progressive. When this rendered clip was viewed on a computer monitor most of the crawling along the edges was gone. [Could not view on the HD screen as I don't have the hardware.]. Their was a little movement in spots but no continous edges.

This may give some idea as to where the problem lies to the experts but I am no expert and have no real opinion. Leave it to you.
Michael

Steve Mullen
December 28th, 2006, 04:22 PM
The raw footage (new section of a brick house) from the camera whether directly viewed via HDMI on a Panasonic HD plasma TV or captured and viewed on a computer monitor shows clearly the crawling brick joins. The same clip shot in 50i mode shows no such abberation.


Since this seems to not be a USA issue I haven't followed this topic. On which edges are the ants crawling?

And is this from a fixed V1E?

Bob Grant
December 28th, 2006, 04:31 PM
When I viewed your original stills in IE6 they originally showed the problem. Using the widget in IE6's viewer to display at native res they pretty well vanished.
Vegas at Preview on the internal preview only shows ever second field, not a good way to evaluate image quality. Also if you turn On Simulate Device Aspect, Vegas induces it's own very nasty artifacts, but from my investigation only does this in PAL, with NTSC it does the reverse, go figure!
One good trick in Vegas I use all the time is to use generated media to simulate the conditions that you think a camera, codec or whatever is having problems with. If you still see the same problem you know that perhaps the problem lies in how you're viewing / processing / displaying the image.

BTW, very few Plasma displays are native 1080 displays, the display is rescaling so that will introduce it's own artifacts.

Michael Phillips
December 28th, 2006, 04:53 PM
The images were taken on a tripod and the plasma TV is a true 1080 HD unit.
The crawling is on the joins in the brickwork and on other clear edges. The real noticable issue is that the 50i does not exhibit this at all, with each clip taken one after the other.
I am not saying nor would I know whether the camera is at fault or whether the way progressive needs to be processed is the problem. Probably if someone in V1-U cuold replicate my takes and see if they have the same issue.
Michael

Steve Mullen
December 28th, 2006, 05:48 PM
The images were taken on a tripod and the plasma TV is a true 1080 HD unit.


Are you sure it has 1920x1080 pixels and is refreshed at 50Hz?

You are feeding it INTERLACED video that is carrying 25p. Hence, the display must deinterlace the signal. I suspect:

1) The display has been set to "film mode" and is assuming a 2-3 cadence.

OR

2) the deinterlacer is screwing up.

OR

3) It's "CUE." By chance does this decription fit -- "spiky horizontal lines?"

I'm betting on #3.

More later.

Michael Phillips
December 28th, 2006, 06:26 PM
The problem is very similar to ants marching horizontally. Not saying that is the correct issue but it describes the closest.
Michael

Steve Mullen
December 28th, 2006, 08:49 PM
The problem is very similar to ants marching horizontally. Not saying that is the correct issue but it describes the closest.
Michael
That's atypical chroma decoder problem.

They move or are static?

Barry Green
December 28th, 2006, 09:01 PM
Can you post a captured .m2t that exhibits the problem?

Michael Phillips
December 28th, 2006, 10:19 PM
They move.
Only on dial up, the M2T would be very helpful.
Michael

Bob Grant
December 29th, 2006, 12:59 AM
OK,
if I get the time tomorrow I'll go grab our V1P, shoot some footage and see if I can post it somewhere. It is the hols so I guess a lot of us are 'asleep'.
I'm just a bit uncertain if this is a camera problem, project I'm working on now shot SD 50i with a DSR-570 has a lot of marching ants and they're my fault. The talent was wearing dayglow orange singlets over blue shirts and those ants are marching all around them, should have known to tell the talent not to wear that specific color. On top of that the high UV output of the lighting in the venue really made the dayglow glow, and crawl.

Also I'll need to install Vegas 7.0c to handle the footage properly.

Tony Tremble
December 29th, 2006, 02:21 AM
There was a lot of stairstepping in the original 25P footage before fix. A strange mix of over softening and aliased edges.

Look at the fence round the running track, perfect on the 50i frame but aliased on the 25P un-fixed frame.

I am wondering if these artefacts remain in "fixed" 25P and could be a result of NLE implementation as the 25P was captured as 50i.

Steve, can you shed some light on things?

TT

Steve Mullen
December 29th, 2006, 02:28 AM
They move.
Only on dial up, the M2T would be very helpful.
Michael

This is classic crawling ants problem, which can't happen with component digital or analog video. :)

I'm sure it's not in the camera, so it must be in the HDTV.

Check the deinterlacer mode. It looks like it's been set to VIDEO rather than AUTO. What brand and model?

Michael Phillips
December 29th, 2006, 02:54 AM
It's a Panasonic TH-42PV500A.
Thanks Michael.

Steve Mullen
December 29th, 2006, 03:05 AM
It's a Panasonic TH-42PV500A.
Thanks Michael.

"The TH-42PV500A can display high definition images, with a resolution of 1024x768 pixels and the ability to show up to 1080i signals."

This isn't a true 1080 HDTV so god knows how it's deinterlacing the video carrying 25p. It's the TV not the camera.

Tony Tremble
December 29th, 2006, 03:17 AM
"The TH-42PV500A can display high definition images, with a resolution of 1024x768 pixels and the ability to show up to 1080i signals."

This isn't a true 1080 HDTV so god knows how it's deinterlacing the video carrying 25p. It's the TV not the camera.

Thank you Steve.

Michael Phillips
December 29th, 2006, 03:27 AM
So it would be better to make a HD DVD or Blue ray through a HD DVD player or whatever after editing to obtain a better result or feeding the signal from my computer to the TV via DVI.
Michael

Martin Mayer
December 29th, 2006, 07:03 AM
Surely the TV's inbuilt scaler is displaying an overscanned image (i.e. cropping the edges) anyway, so it cannot be a pixel-for-pixel image, or even close?

Steve Mullen
December 29th, 2006, 05:16 PM
So it would be better to make a HD DVD or Blue ray through a HD DVD player or whatever after editing to obtain a better result or feeding the signal from my computer to the TV via DVI.
Michael

The TH-42PV500A is a inexpensive unit with nothing in the manual on setting the interlace mode for film vs video. It likely simply scaling each field from 540 to 768 for each 1/50th S.